diff --git a/ylgamehall/RootViewController.swift b/ylgamehall/RootViewController.swift
index 6f76861..c42f04c 100644
--- a/ylgamehall/RootViewController.swift
+++ b/ylgamehall/RootViewController.swift
@@ -128,6 +128,28 @@ final class RootViewController: UIViewController {
                       远端 gameVersion  = \(resolved.gameVersion)
                       → H5 zip 升级    = \(needZipUpgrade ? "需要" : "不需要")
                     """)
+
+                    // Phase 1.13 烟雾测试：触发 LobbyZipUpgrader（如果需要升级）
+                    let upgradeStart = Date()
+                    do {
+                        let outcome = try await LobbyZipUpgrader.shared.upgradeIfNeeded(resolved: resolved)
+                        let elapsed = Date().timeIntervalSince(upgradeStart)
+                        switch outcome {
+                        case .noop:
+                            print("""
+                            [LobbyZipUpgrader] 无需升级，跳过（耗时 \(String(format: "%.3f", elapsed))s）
+                            """)
+                        case .upgraded(let from, let to):
+                            let newLocalGame = LocalVersionReader.localGameVersion
+                            print("""
+                            [LobbyZipUpgrader] 升级完成 \(from) → \(to)（耗时 \(String(format: "%.3f", elapsed))s）
+                              重新读 version.xml: localGameVersion = \(newLocalGame)
+                              lobbyIndex 存在: \(FileManager.default.fileExists(atPath: SandboxPaths.lobbyIndex.path))
+                            """)
+                        }
+                    } catch {
+                        print("[LobbyZipUpgrader] ERROR: \(error)")
+                    }
                 case .shortText(let msg):
                     print("""
                     [RemoteConfigClient] 拉到短文本响应（耗时 \(String(format: "%.3f", elapsed))s）
diff --git a/ylgamehall/Source/Resource/LobbyZipUpgrader.swift b/ylgamehall/Source/Resource/LobbyZipUpgrader.swift
new file mode 100644
index 0000000..ed81570
--- /dev/null
+++ b/ylgamehall/Source/Resource/LobbyZipUpgrader.swift
@@ -0,0 +1,101 @@
+//
+//  LobbyZipUpgrader.swift
+//  ylgamehall
+//
+//  H5 zip 升级：下载远端 game_zip → 临时目录解压 → 原子 rename 到 lobbyRoot。
+//  详见 docs/Development-Plan.md ADR-008-G / Design §6.3.4 / msext NewRootVC.m:1789-1869。
+//
+
+import Foundation
+import ZIPFoundation
+
+public actor LobbyZipUpgrader {
+
+    public static let shared = LobbyZipUpgrader()
+
+    public enum Outcome: Sendable {
+        /// 本地版本已是最新（含远端 gameZip 为空 / 版本号未提升的情况），未做任何下载
+        case noop
+        /// 完成升级。`from → to` 是版本号变化。
+        case upgraded(from: Int, to: Int)
+    }
+
+    public enum UpgradeError: Error, Sendable {
+        case badGameZipURL(String)
+        case downloadFailed(any Error)
+        case httpStatus(Int)
+        case unzipFailed(any Error)
+        case stagingMoveFailed(any Error)
+    }
+
+    private let session: URLSession
+
+    public init(session: URLSession = LobbyZipUpgrader.defaultSession) {
+        self.session = session
+    }
+
+    /// 默认 URLSession：下载用 60s 超时（zip 大约 11 MB，4G 网络约 10s）。
+    nonisolated public static var defaultSession: URLSession {
+        let cfg = URLSessionConfiguration.default
+        cfg.timeoutIntervalForRequest = 60
+        cfg.timeoutIntervalForResource = 300
+        return URLSession(configuration: cfg)
+    }
+
+    /// 比较远端 game_version 与本地 version.xml。需要升级则下载 + 解压 + 原子 rename。
+    ///
+    /// - Parameter resolved: VersionResolver.resolve(...) 的结果
+    /// - Returns: `.noop` 已是最新；`.upgraded(from:to:)` 完成升级
+    public func upgradeIfNeeded(resolved: ResolvedVersion) async throws -> Outcome {
+        let localGameVersion = LocalVersionReader.localGameVersion
+        guard resolved.gameVersion > localGameVersion,
+              let zipURLString = resolved.gameZip,
+              let zipURL = URL(string: zipURLString)
+        else {
+            return .noop
+        }
+
+        // 1. 下载到 tmp（URLSession 默认管理临时位置）
+        let downloadedURL: URL
+        let response: URLResponse
+        do {
+            (downloadedURL, response) = try await session.download(from: zipURL)
+        } catch {
+            throw UpgradeError.downloadFailed(error)
+        }
+        if let http = response as? HTTPURLResponse,
+           !(200..<300).contains(http.statusCode) {
+            throw UpgradeError.httpStatus(http.statusCode)
+        }
+
+        // 2. 解压到隔离 staging 目录
+        let staging = SandboxPaths.caches
+            .appendingPathComponent("lobby-staging-\(UUID().uuidString)")
+        let fm = FileManager.default
+        do {
+            try fm.createDirectory(at: staging, withIntermediateDirectories: true)
+            try fm.unzipItem(at: downloadedURL, to: staging)
+        } catch {
+            try? fm.removeItem(at: staging)
+            throw UpgradeError.unzipFailed(error)
+        }
+        try? fm.removeItem(at: downloadedURL)
+
+        // 3. 原子 rename：删旧 lobbyRoot → 把 staging 移到位
+        //    （msext "removeItem + ZipArchive overWrite:YES" 半途崩溃留半残；
+        //     我们 staging 完整解压后再 rename，半途崩溃只留 staging，下次启动可清）
+        let lobbyRoot = SandboxPaths.lobbyRoot
+        do {
+            if fm.fileExists(atPath: lobbyRoot.path) {
+                try fm.removeItem(at: lobbyRoot)
+            }
+            // 父目录确保存在（Library/Caches 永远存在，无需创建中间路径）
+            try fm.moveItem(at: staging, to: lobbyRoot)
+        } catch {
+            try? fm.removeItem(at: staging)
+            throw UpgradeError.stagingMoveFailed(error)
+        }
+
+        return .upgraded(from: localGameVersion, to: resolved.gameVersion)
+    }
+}